Genetic diversity and differentiation of the Hainan Tall coconut (Cocos nucifera L.) as revealed by inter-simple sequence repeat markers

Hainan Tall coconut (Cocos nucifera L.), which show the advantageous characteristics of high yield, hardiness, and wind resistance, is the dominant coconut population in Hainan Island, the main area of coconut production in China. An understanding of the genetic diversities and origins of the Hainan Tall population is essential to effective breeding. To achieve this aim, we used dozens of inter-simple sequence repeat molecular markers to characterize the genetic diversity among Hainan Tall and other coconut accessions outside China. Results revealed that Hainan Tall consisted of two main subgroups reflecting different geographic distributions (such as northern vs. southern parts of Hainan Island), and other accessions lacking clear location trends because of human activities. Diversity analysis revealed that the Hainan Tall population exhibits a higher genetic diversity than that of exotic populations mostly collected from Southeast Asia. The phylogenetic clustering results indicated that the Hainan Tall population is domesticated separately from (and earlier than) other coconut accessions, and the differentiation existed within the Hainan Tall population. Among other causes, this notion may explain the high diversity within the Hainan Tall population. Overall, these findings provide a preliminary scenario of the genetic diversities and origins of the Hainan Tall population.